The miniaturization of information storage devices has been accompanied by increases in storage density, device capacity, and access speed (i.e., read and/or write speeds). Such devices, which include hard disk drives, optical disks, and the like, generally include a substrate on which various coatings or layers (e.g., a lubricant layer, an adhesion promotion layer, a passivation layer, a magnetic material layer, and other like layers) are deposited.
These coated substrates can spin between about 4200 and about 15000 revolutions per minute (rpm) during read and/or write operations, with read/write heads that can be positioned as close as a few nanometers (nm) from the spinning, coated substrate. At these access speeds and head distances, even small defects in the surface of the substrate (and, by extension, the surface of the outermost coating disposed on the substrate) will cause unacceptable errors during operation. In addition, as thinner substrates are implemented in an attempt to reduce the size of the final device, substrate stiffness can affect performance. That is, at such high access speeds, the substrate can undergo out-of-plane deflections, which also will result in unacceptable errors during operation. Thus, in order to continue to achieve further improvements in size and performance, the information storage devices will need substrates that are thinner, more rigid/stiff, and smoother.
Currently, substrates for such devices are formed using aluminum, glass, or ceramics. These materials are subjected to intensive chemical and/or mechanical processing (e.g., acid and/or base cleaning, mechanical grinding, polishing, edge shaping, interior orifice cutting/shaping, and the like) to provide the appropriate thickness and smoothness levels. In addition to being costly, the additional processing steps to which the substrates are exposed have the potential to introduce additional defects and/or reduce the stiffness of the substrate material.
There accordingly remains a need for substrates and substrate materials for information storage devices that have improved stiffness and surface smoothness properties while having a sufficiently low thickness values. It would be particularly advantageous if such substrates and substrate materials could be formed in such a manner that would result in post-fabrication chemical and/or processing steps, if needed, having minimal to no effect on the surface smoothness or stiffness properties thereof. It is to the provision of such technologies that the present disclosure is directed.